Drier



Sept. 30 1924. I 1,510,307

L; R. CHRISTIE mvsm'o if? N I Sept. 30 1924. 1,510,307

L. R. CHRISTIE DRIER Filed July 3, 1923 2 Sheets-Sheet 2 INYENT R. a j W Patented Sept. 30, 1924.

UNITED STATES PATENT OFFICE.

LINDSAY R. CHRISTIE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR OF ONE-HALF T'O DUFF PATENTS COMPANY. INCORPORATED, OF PITTSBURGH, PENNSYLVANIA,

A'GOfiPORATION OF PENNSYLVANIA.

DRIER,

Application filed July 3,

To all whom it may concern:

Be it known that I, LINDSAY H. Cnius'rin, a citizen of the United States, residing at Pittsburgh. Allegheny County, Pennsyl- Vania, have invented a new and useful lmp-rovement in Driers, of which the following is a full, clear, andexaot description.

The present invention relates to driers, and more particularly to combined indirect and direct heat driers for use in dryin powdered and granular or clayey materia An important object of the invention is the provision of a. drier of the general type disclosed in my Patent No. 1,332,380, but embodying a rotary drum having an inner shell so shaped in cross section as to provide a greatly increased heat transfer surface over that provided by a. cylindrical shell enclosing an equivalent space, with a corresponding increase in efliciency of operation.

Another object of the invention is to provide an inner shell tending to hold the material being dried thereon.

In the accompanying drawings, there is shown, for purposes of illustration only, a preferred embodiment of the present invention. it being understood that the drawings do not define the limits of my invention, as changes may obviously be made in the construction therein disclosed, without departing from the spirit of the invention or scope of the broader claims.

In the drawings:

Figure 1 is a central vertical longitudinal sectional view through a drier constructed in accordance with my invention;

Figure 2 is a transverse vertical sectional view on the line 11-11 of Figure 1; and

Figure 3 is a transverse vertical sectional view on the line III-III of Figure 1.

As illustrated in the drawings, my improved drier comprises a rotary drum A, supported for rotation upon rollers 2, engaging tracks 3 on the drum, said drum being arranged at a slight inclination to the horizontal and rotated by suitable means, including a pinion 4, engaging a gear 5 on the drum.

The drum A comprises an outer cylindrical shell 6, and an inne-rshell 7, which may preferably have in cross section substantially the shape of a Greek cross. This shape of inner shell provides a much greater heat transfer surface than a cylinder enclosing an 1923. Serial No. 649,207.

equivalent space, with advantages which will be brought out hereinafter.

The inner and outer shells are separatcld "from each other to form a material-receiving space 8 between the same by supporting arms 9, connected at their ends to the shells to permit of unequal expansion in the latter, as customary in the art. At the forward end of the drum, the radial arms of the cross-shaped inner shell are extended outwardly to form nozzles 10, opening through the outer shell and through which hot conr bustion gases from a furnace 11 may enter the inner shell.

The material to be dried is introduced into a cylindrical compartment 12, at the extreme front end of the drum through a stationary hopper 13. The compartment 12 is provided with helical flights 14, by means of which the material entering the compartment is conveyed to the spaces 15 between the nozzles 10 (Figure 3). The rotation and inclination of the drum then cause this material to pass into the space 8 between the inner and the outer shells. The outer shell 6 is provided in said space with cascading flights 16, which pick up the material as it passes through said space and deposit it upon the inner shell 7. The radial arms of this shell are provided at their outer ends with flanges 17, which tend to hold the material on the inner shall. It will be noted, however, that the angles formed between the flanges 17 and the walls of the inner shell and the angles formed between the radial arms of the inner shell are each at least as great as a right angle, so that'there is no tendency for the materialto stick in said angles and become dried to such an extent that the hot combustion gases will burn the walls of the shelL as might happen if such angles were acute angles tending to bind or pack the material therein.

After passing through the space 8 between the inner and the outer shell, the-material enters a cylindrical compartment 18 at the rear end of the drum. This compartment is provided with flights 19, which catch the material and discharge it through the chute *20. The hot gasesentering the inner shell 7 through the nozzles 10 travel through said inner shell and thence around the rear end thereof and return through the space 8 between the inner and outer shells. After giving up their heat, they are exhausted by a fan'lll, mounted on top of the furnace l1 and having an exhaust flue 22, communicating with the compartment 12 at the front end of the drum. During their passage through the inner shell, the hot gases indirectly heat and partially dry the material in the space 8 the large heat transfer surface provided by the inner shell and the holdin of material on the inner shell by means of the flanges and angles I? greatly assisting this action. This lowers the temperature :of these gases to such an extent that when they come into direct contact with the material in the space 8, they will cause no dam age to such material. This showering of the material by the flights 17 breaks up the same and further facilitates the desired heat interchan e.

By so s aping the inner shell in cross section so as to provide a flue having a plurality of radial. arms, the shell surface is greatly increased over that of a cylindrical shell enclosin an equivalent space, with the result that t iere is a greater transfer of heat by the indirect method, so that the temperature of the gases when they come in direct contact with the material at the dry or discharge end of the drum is greatly reduced. The material is not overheated and there is less heat wasted on this account, as well as an increase in the efficiency of the apparatus in general. By this construction. it is also possible to reduce the cross sec tional area of the center flue and still increase the amount of heating surface. This permits a higher gas velocity through the center flue, thereby increasing the capacity of the drier without impairing its eiiiciency. The increased gas velocity has another important function in that it serves to more efficiently remove from the inner surface of the flue adhering bubbles of spent gas. which tend to form a heat-insulating curtain on such surfaces.

I claim:

1. In a drier. a rotatable drum comprising an outer shell and an inner shell providing a single compartment between the same throu hout the major portion of the length of t e drum for receiving material to be dried, said inner shell forming a flue for heated gases and communicating at its rear end with said space. said flue being shaped in cross section to provide a plurality of angularly related radial arms. substantially as described.

2. In a drier. a rotatable drum comprisin an outer shell and an inner shell pro riding a space between the same for receiving material to be dried, said inner shell forming a fine for heated gases and communicating at its rear end with said space, said flue being shaped in cross section to provide a plurality of radial arms having the angles therebetween each at least as great as a right angle substantially as described.

In a rier, a rotatable drum comprising an outer shell and an inner shell providing a space between the same for receiving material to be dried, said inner shell forming a flue for heated gases and communicating at its rear end with said space, said flue being shaped in cross section to provide four radial arms arranged at right angles to each other, substantially as described.

4. In a drier, a rotatable drum comprising an outer shell and an inner shell providing a space between the same for receiving material to be dried, said inner shell forming a flue for heated gases and comma nicating at its rear end with said space. said flue being shaped in cross section to provide a plurality of angularly related radial arms. said arms being .rovided with means tending to hold material thereon. substantially as described.

5. In a drier. a rotatabe drum comprising an outer shell and an inner shell providing a space between the same for receiving material to be dried, said inner shell forming a flue for heated gases and communicating at its rear end with said space, said. flue being shaped in cross section to provide a plurality of radial arms having the angles therebetween each at least as great as a right angle, said arms being provided with means tending to hold material thereon. substantially as described.

6. In a drier. a rotatable drum comprising an outer shell and an inner shell providing a space between the same for receiving material to be dried. said inner shell forming a flue for heated gases and communicating at its rear end with said space. said flue being shaped in cross section to provide a plurality of radial arms. said arms being provided at the. outer ends thereof with flanges projecting at right angles to the walls of said arms for holding the material thereon. substantially as described.

7. In a drier. a rotatable drum comprising an outer shell and an inner shell pro riding a space between the same for receiving material to be dried, said inner shell forming a flue for heated gases and communicating at its rear end with said space, said flue being shaped in cross section to provide a. plurality of radial arms, said arms being provided with means tending to hold ma terial thereon. and cascading means within said space and projecting from the said outer shell. substantially as described.

In testimony whereof I have hereuto set.

my hand. 7

LINDSAY R. CHRISTIE. 

